Thermostat for electric circuits



E. COLLINS, 3D

THERMGSTT FOR ELECTRIC CIRCUITS Aug. 16, 1938.

Filed Aug. 27, 19155 r, w W m www www www www: 6 I ...m am

Patented Aug. 16, 1938 UNETED STATES alzarse THERMOSTAT FOR ELECTRIC CIRCUITS Edward Collins, 3rd, Philadelphia, Pa.

Application August 4'27 5 Claims.

This invention relates to mercurial thermostats used in connection with electric circuits.

The control of temperature in the use of many things and processes is important in many industries, laboratory work and in various kinds of researches. Such control with precision has much to do with the kind of results obtained, particularly where automatic constant control of temperature is most desirable. To enumerate some of the instances where such control of temperature is an important factor, mention might be made of crystal temperature control for radio transmitters and kindred appliances, the rubber industry, both natural and artificial, incubation, milk sterilizers, the oil industry, air conditioning, including heating and Ventilating, and humidity control, warming cabinets, industrial baths relative to processes of manufacture, baking, heat treating of cereals for the trade, chemical processes, germ culture, certain machinery, bearings, the manufacture of paints, drugs., etc., automatic ire extinguishing apparatus and commercial temperature control. In fact, a precision instrument for the automatic and constant control of heat, that can be depended upon, becomes an important factor as an .addition to equipment used in any of the above instances mentioned and in many more.

The main object of my invention, therefore, is to provide a mercurial thermostat for electric circuits, adapted for use as a contact making thermometer where precision, as well .as constant temperature control is highly desirable, having the thermostat of simple construction, and practical to manufacture, while at the same time affording a delicate manual adjustment, within a fraction of .a degree, to close or open an electric circuit for regulating heat for whatsoever purpose desired.

In connection with this main object, I desire thc said construction to include a mercury bulb and stem, preferably similar to a thermometer, except having the bulb of a spheroid shape, capable of being slightly flattened in the direction of the axis of that part of the tubular stem, integral with the bulb, which is immediately adjacent to bulb, regardless of whether the remaining part of the stem continues straight or at an angle to stem portion, adjacent the bulb.

In connection with the thermostat, fulfilling this main object, I desire to have means, manually adjusted to eXert a pressure upon the bulb, to sufficiently distort the same to cause the mercury to rise in the stem, to close a circuit between two terminal wire ends, positioned Within 1935, Serial No. 38,077

(Cl. 20G-141) the path of the mercury, as it is caused by the pressure on the bulb to rise Within the stem while maintained at a given temperature, which directly iniiuences atthe same time, the mercury within the said bulb and stem. Y

A further object is to pro-vide means for man ually and delicately adjusting the pressure upon the bulb of the thermostat, either adjacent the casing of the thermostat, or by remote control, having additional means to hold the adjustment secure, once it is set.

In connection with the last named object, I desire to provide a plurality of adjustments in connection with the .adjusting means for changing to a coarse or ne adjustment, using the same operating means.

Another object of my invention is to provide a thermostat construction, which, while fulfilling any or all of the above named objects, will be practical to manufacture in quantities, and while providing a closely adjustable instrument, will not be costly to make and will lend itself practically along the lines of thermometer production, in the making of the mercury lled glass stem and bulb parts of the thermostat.

With these and other objects which will hereinafter appear, my invention resides in certain construction of mercurial thermostats, two embodiments of which ,are illustrated in the drawing. The same is described, the functioning of the parts is explained, and what I claim is set forth.

In the drawing,

Figure 1 is a front elevation of a thermostat embodying my invention.

Figure 2 is a sectional, side elevation taken on the line 2 2 of Figure 1.

Figure 3 is a rear perspective view of the upper part of the thermostat shown in Figures 1 .and 2.

Figure 4 is a perspective View of the upper part of the compressing lever, shown also in Figures 1 and 2.

Figure 5 is a front elevation of another fo-rm of thermostat, embodying my invention.

Figure 6 is a sectional side elevation, taken on the line 6 6, of Figure 5, and here shown attached to a wall.

Figure l is an elevation showing the front flat side of the compressing lever with attachments, which are shown also in Figures 5 and 6.

In the figures, considering Figures 1, 2, 3 and 4, the casing l0 is shown to have an open back Il, integral with sides l2 and I3, top portion I4 and bottom portion l5. Hinged upon the crossrod I6, near the top portion I4, is an L-lever I'l,

having an upper portion I8, with ears I9, journaled upon the cross-rod I6, xed in the sides I2 and I3. A stem seat 20, depends from the upper portion I8, of the L-lever I1. Integral with the portion I8, is the long arm 2l, which is positioned adjacent to the back II. Fixed in the bottom portion I5 is a bushing 22, in threaded engagement with the screw 23, which has a cup portion 24, and a knurled finger end 25. Between the stem seat 28 and the cup portion 24, of the screw 23, is the glass thermostatic element 26, having a bulb 21, flattened in the direction of the axis of the element, and having a tubular stem 28, between the bulb 21 and the stem seat 20. The bulb 21 and the tubular stem 28, are in open communication, having mercury 29 nlling the bulb 21, and extending partly up the channel 3D, of the stem 28. Considering particularly the structure of the bulb end of the glass thermostatic element 26, as shown in section, in Figure 2, the central part of the upper cross wall portion of the bulb 21, is also the lower solid glass end of the channeled stem 28, and is therefore inflexible within the Zone 39. Directly opposite this upper cross wall portion, of the bulb, is the lower cross wall portion, having its central part inflexible, inasmuch as it is part of the lug 38, thus leaving any flexible action of the bulb to be had only from the thin, curved wall portions of the bulb, outside of the upper and lower, central, and inflexible wall portions of the bulb, which are concentric with the axis of the stern 25.

Penetrating the wall of the stem 28 and entering the channel 30, are the metal wires 3I and 32, connected respectively to the metal rings 33 and 34, bound on the outside of the stem 28. Connected with the `rings 33 and 34 are the respective terminal pieces 35 and 36, with eyelet ends 31. Where the thermostatic element 26 rests in the cup portion 24, of the screw 23, there is a solid glass lug 38, integral with the bulb 21. Considering this bulb 21, the Walls thereof, the upper flattened portion has a zone 39, surrounding the end of the stem 28, so that any end pressure coming from the stem 28 will tend to depress the zone portion 39, of the bulb 21, and reduce the size of the cavity of the bulb 21, holding the mercury 29, causing the latter to rise in the channel 30, of the stem 28.

Returning to the L-lever I1 and its long arm 2|, there is shown a screw 48, in threaded engagement with the upper bushing 4I, fixed in the back II, of the casing I0. Midway of the height of the casing IU, I have provided another bushing 42, threaded for engagement with the screw 40, when it is desired to change the screw 39, from engagement with the bushing 4l, to engagement with the bushing 42, so that the .screw 48 can bear against a portion of the arm 2|, further away from the journaled connection of the L-lever I1, with the rod I6, when one turn of the screw 48 will cause considerably less angular movement of the L-lever I1 than one turn of the screw will cause, in conjunction with the upper fbushing 4I, with which the screw 4D is shown engaged in Figure 2.

The permissible lower position of the screw 4i), is shown in broken lines, at 48a. The screw 45 may have its outer end provided with the usual finger piece, near the housing, or it may be provided with a remote control device, as shown in the upper parts of Figures 1 and 2, including a fluted head 43, engaged by a pawl piece 44, having an elastic arm 45, fixed in a post 48, which itself is fixed in the housing ID, so that we have a pawl and ratchet connected with the screw 40, for retaining the same in any angular position it is put by adjustment.

Fixe-d to the screw head I3 is a flexible shalt ll'I, terminating in a finger piece 48. This shaft l? may be any length desired and as a flexible shaft to turn the screw lll from a distance. For a safety stop, I provide a pin 5.9, fixed in the head 43, positioned, and long enough, to

come against the post 45, to prevent any excessive turning of the screw M3, which would tend to evert too much pressure upon the bulb 21.

Considering now the modiied form of my invention, shown in Figures 5, 6 and 7, there is a casing 50, having an open back 5I, sides and top portion 53. Fixed to the casing 58, by spot welding or otherwise, is a bracket 55., having legs 55 and 55 with out-turned portions 51, through which pass screws 58, into a wall 59. Fixed to the inside of the back 5I, are collars 88 and 6I, which support the hollow stem 82, of the glass tl'iermostatic element 53. This stem 82 is shown to be bent at 54, where the vertical portion 55, and the horizontal portion. 88, merge. The portion 58 passes through a large hole 61, in the back 5I, oi the casing 58, and through a smaller hole in the plate 58, attached within the bracket 54.

Seated against the lips of the hole 58, in the plate 59, is the flattened bulb 1li, integral with the stem 82. The bulb 1) has within it mercury 1|, which passes part way into and up the channel 12, of the stem 82. The bulb and stein E2 are preferably made of suitable glass. Extending from the bulb 18, centrally, to the rear, is the solid glass lug 13, which is seated in the pocket 14, of the fiat lever 15. This lever 15 is hinged with the eye 16, of the bolt 11, which passes through a slot 18, in the leg 55, of the bracket 54. The slot 18 extends lengthwise of the leg 55 for adjusting the position of the bolt 11, with respect to positioning the lever 15, relative to the lug 13. The bolt 'I1 is secured to the leg 55 by nuts 19.

Journaled in the lower end 89, of the lever 15, is the screw 8l, having a washer 82a, fixed thereto. The screw 8l is threaded with the plate 59, the bracket 54, and thel casing 58. rIhe outer end of the screw 8l has a head 82, with longitudinal teeth 83, forming a ratchet with the spring pawl piece 84, fixed in the post 85, which is fixed in the bracket 54 and the casing 50. Part of a flexible shaft 36, similar' to that illustrated in Figures l, 2 and 3, is shown fixed to the head 82.

Considering the electric terminals of the instrument shown in Figures 5 and 6, the wire ends 81 and 88 positioned within the channel 12, are connected through the wall of the stem 82 with the metal rings 89 and 96) respectively. which are bound around the stem 62. Connected with the rings 89 and 9U are the respectiveA terminal pieces 9! and 92 having eyelets 93.

In operation, assume that the bulb 21, of the thermostat shown in Figures l and 2, is either immersed in a liquid or surrounded by a gas or air, as the case may be, and that the temperature of the medium thus surrounding the bulb 21 is the same as that at which it is desired to check and hold the heat, elfectng the object or process to be governed, assuming there to be present, at such object or along with the appliances for carrying out a pro-cess, an electrical controlling device, in circuit with the terminals at 3l and 32, which will operate, as desired, to effect a temperature control, upon the closing of a circuit. Then, while at this given temperature, the screw 40 is turned to bear against the arm 2|, of the L-lever I1, causing it to turn about the cross-pin IB and bear down at the stem seat 2B, so that the tubular stem 28 is caused to move slightly downward, in the direction of its axis, and depress the zone portion 39, of the upper wall of the glass bulb 21, and cause the mercury 29 to rise in the stem channel 30, passing the wire end 32 and contacting the wire end 3i, closing the circuit.

The operator carefully observes the instant at which the circuit is thus closed, and he stops turning the screw 4Q, at that instant. The screw 4t may be turned either by directly turning the head 43, or by using the flexible shaft 41, by turning it at the finger piece 48, as at a point of remote control. In order to hold the screw 4U at the point where the operator stops turning the same, the pawl member 44 will engage the teeth of the head yet permit the turning of the screw 4l), manually either way. Unscrewing the screw 4@ causes the mercury in the stem 28 to recede downward, breaking the circuit.

In the event that it is desired to effect a more delicate adjustment, by means of the same screw the screw 49, with its connections, is changed from engagement with the bushing 4I, to engagement with the bushing 42, to occupy the position so as to bear against the arm 2|, at a point further away from the pin I5, upon which the L-lever l1, swings. In this latter case, one turn of the screw llt, will cause much less downward movement of the stem 28, and therefore a less or slower rise of the mercury within the channel 30. If desired, ratchet means, having parts similar to 44, i5 and 46, can be provided also about the bushing 2, to function with the head 43, when the screw 4@ engages the bushing 42. Once the thermostat has been set to close a circuit at the temperature desired, then as soon as this temperature falls, the mercury column will automatically fall, opening the circuit which will stay open, until the temperature is caused to rise again and send the mercury back up the channel Si), to again close the circuit at the temperature, at which it had been set.

Next, having the thermostat positioned Where it will be eiected, simultaneously, by the same degree of heat, which eiects the object or process under consideration, the functioning of the thermostat will automatically close the circuit, at the desired temperature, or open the circuit below said temperature for which it has been set, to govern the operation of the electrical device with which it is in circuit, and which directly causes a rise or fall in temperature at the said object, whose temperature it is desired to govern, or in connection with the process being carried out chemically or otherwise.

Referring now to the operation of the modiiied form oi mercurial thermostat shown in Figures 5 and 6, a pressure upon the bulb 10, in the direction of the axis of that part 66 of the bulb stem 62, will cause the mercury to rise in the channel 12, to close a circuit between the terminal wire ends 81 and 8S, in a similar way to that described above in connection with the terminal wire ends Si and 32, of the thermostat, shown in Figures 1 and 2 and for similar purposes. While a rise of mercury in either channel 30 or 12 can be caused by pressure upon the respective bulbs 21 and 10, there is a difference in which these bulbs are compressed, although each is compressed in the direction of the axis of that part of the stem immediately adjacent the bulb. Where pressure upon the bulb 21 is brought from the remote upper end of the stem 28, and is brought upon the bulb 21 by the stem itself, pressure upon the bulb is exerted directly upon the bulb between the plate 69, directly in contact with the bulb 10, and the lever in pressing contact with the lug 13, integral with the bulb 10. This pressure is produced by means of the drawing eiTect exerted by unscrewing the screw 8i upon the lever 15, the screw being turned manually by a flexible shaft 86, connected with tho head 83, and held where adjusted by the ratchet means including the pawl member 84. As a matter of precaution against excessive turning of either the head 83, or the head 43 of the form shown in Figures 1 and 2, I provide the respective projecting pins 81 and 49, which are adapted to stop against the respective posts 85 and 4l.

In this application we are primarily concerned with the thermostatic construction herein illustrated and described as embodying my invention and while no specific electrical governing device for immediate connection with the thing or process requiring heat control, is shown, it will be readily understood by those skilled in the art of thermostats, how to make any specific applications of my invention for precision temperature control, particularly where such precise control of temperature is to be constant in connection With the electrical governing device used in the several instances mentioned above and many more.

While I have above referred to an individual use of said thermostat embodying my invention, it is possible to use a plurality of such instruments for temperature control, by having the instruments, each set for closing a circuit at a different temperature, in connection with processes or objects, where a succession of various temperatures is desired to be had, each for a given period of time, using a timing device to denitely measure the time of duration of the control of each thermostat, or for this same purpose, instead of using a plurality of such mercurial thermometers, we can have more than two spaced terminals along the line of the mercury channel, in which case the bulb adjustment would only be possible as eiecting the lower two of said terminals, as the spacing of the remaining termials within the said channel would be constant.

Inasmuch as other modifications than` those shown and described can be made, without departing from the spirit and scope of my invention, I wish to include all forms of structure, which come within the purview of the following claims.

I claim:

l. A mercurial thermostat for use in closing an electric circuit, said thermostat including a casing, a mercury thermometer, a bent stem' to said thermometer, a channel running longitudinally within said bent stem, mercury within said bulb and said channel, terminal means in said circuit entering said channel in spaced relation from the outside, holding means for securing said thermometer to said casing, said bulb being flattened in the direction of the axis of that part of said stem immediately adjacent said stem, a lug extension on said bulb opposite to and in line with the last mentioned part of said stem, a bracket attached to said casing positioned near said bulb, a leg to said bracket extending at an angle to said casing, a slot in said leg, extending longitudinally of the same, a bolt through said slot secured adjustably by nuts to said leg, a lever pivoted to said bolt and positioned to be across said lug and in contact therewith, a seat for said bulb having a hole therein through which said stem part next to said bulb passes said seat being connected with said casing, and means for adjustab-ly forcing said lever against said lug, to compress said bulb against said seat, to force said mercury up said channel to close the circuit between said spaced terminal means.

2. A niercurial thermostat made in accordance with claim 1, having in addition retaining means for retaining the adjusted compression of said bulb.

3. In a mercury thermostat including a casing, a thermometer having a stem, a bend in said stem, with a longitudinal mercury channel to said stem, and a mercury bulb, electric terminals ending in spaced relation in said stem channel, a seat for said bulb on said casing, positioned opposite the termination of said stein at said bulb, and means for adjustably forcing said stem, in the direction of its length to compress said bulb between said stem and said seat to cause said rise in said channel to close a circuit between said terminals.

4. In a thermostat having a housing, a thermostatic mercurial element of glass including a mercury bulb, with an integral lug on one side, and a tubular stem on the opposite side, of said bulb, terminal wire ends within the mercury channel of said stem, with electrical terminal means connected with said wire ends, and having said stem bent, a bulb compressing means, comprising, a IiXed seat for said bulb, said stern passing through said seat, a pivcing element on said housing, a lever pivoted upon said element and bearing midway or its length, against said lug, and means for adjustably forcing said lever to bear against said lug to compress said bulb to cause said mercury to rise in said channel to close a circuit between said Wire ends.

5. A mercurial thermostat for use in closing an electric circuit, said thermostat including a casing, a mercury thermometer mounted on said casing, a stem to said thermometer, a hollow bulb at one end of said stem, a channel ruiming longitudinally Within said stem, communicating with the interior of said bulb, mercury within said channel and said bulb, terminal means in said circuit, entering said channel :in spaced relation, through said stern from the outside, a globular wall forming said bulb, a solid portion to said globular wall formed by the merging of said stem with said bulb, a pressure receiving portion to said globular wall, positioned opposite to said solid portion, a iiexible portion to said globular wall comprising the remaining part of globular Wall between said solid. portion and said pressure receiving portion or said wall, and adjustable means for pressing against said pressure receiving portion, in the direction oi said solid portion to cause said mercury to rise mechanically in said stem,

EDWARD COLLINS, 3RD. 

